Cancer patients who exercise tend to do better than those who do not. While one cannot escape an established cancer via physical activity, one can modestly slow it down, it appears. Researchers here explore some of the mechanisms by which exercise can achieve this goal, focusing on muscle tissue signaling that both slows cancer cell growth and provokes greater immune system activity. The usual path forward for this sort of research, given a large enough effect size to be interesting, is to try to find a way to deliver additional signal proteins as a form of treatment. This might be achieved directly using recombinant protein therapy, or via some form of small molecule drug that upregulates signal protein expression. In either case, that is a road of some years from present understanding to eventual therapy, and it isn't at all clear that the size of the effect justifies that effort.
Exercise causes muscles to secrete proteins called myokines. Researchers have learned these myokines can suppress tumour growth and even help actively fight cancerous cells. A clinical trial saw obese prostate cancer patients undergo regular exercise training for 12 weeks, giving blood samples before and after the exercise program. Researchers then took the samples and applied them directly onto living prostate cancer cells.
"The patients' levels of anti-cancer myokines increased in the three months. When we took their pre-exercise blood and their post-exercise blood and placed it over living prostate cancer cells, we saw a significant suppression of the growth of those cells from the post-training blood. That's quite substantial indicating chronic exercise creates a cancer suppressive environment in the body."
while myokines could signal cancer cells to grow slower - or stop completely - they were unable to kill the cells by themselves. However, myokines can team up with other cells in the blood to actively fight cancer. "Myokines in and of themselves don't signal the cells to die. But they do signal our immune cells - T-cells - to attack and kill the cancer cells."